A trocar-cannula, or simply, a trocar, is a surgical device used to obtain access to a body cavity to perform various surgical procedures, for example, laparoscopic surgery or arthroscopic surgery. The trocar is an elongated, pointed surgical instrument having a pointed rod-like device, referred to in the art as an “obturator”, that is fitted into a tube-like device that is referred to in the art as a “cannula”. The pointed, sometimes sharply pointed, end of the obturator projects out the end of the cannula and is used to penetrate the outer tissue of the cavity. After the tissue is penetrated and the body cavity, for example, is accessed by the trocar, the obturator is withdrawn from the cavity and the cannula is left in place in the cavity to provide a channel for accessing the cavity. The body cavity can then be accessed by further surgical instruments via the cannula to perform various surgical procedures, or the cannula can simply be used as a drainage outlet. Among other uses, trocar devices are typically used to penetrate the human abdominal wall to gain access, for example, to the organs within.
One prior art trocar is the device disclosed in commonly-assigned U.S. Pat. No. 5,824,002. This patent discloses a “transition-less” trocar, that is, a trocar which provides a smooth geometric transition between the tip of the obturator to the end of the cannula so that the trocar can be inserted with reduced force compared to trocars having an abrupt geometric transition while reducing the potential for damaging tissues. However, there is still a need in the art to further reduce the potential for damaging tissue, sutures, and the instruments themselves and there is still a need to further reduce the force and effort that need be exerted by the surgeon.
These and other desirable features for trocars and their use compared to the prior art are provided by the present invention and will become readily apparent upon review of the following summary, detailed description, and claims.